How accurate are weight predictions via ultrasound?

**sas85** · July 5th, 2010, 01:45 PM

At 34 weeks they told me DD2 was 2.5kg so spot on the 50th % - well 6 weeks later DD2 was born at 2.96kg (more like the 10th %) so either it was way out, or she gained under 500g in 6 weeks which is I suppose possible as I don't feel my tummy got much bigger.

**carr2walks** · July 9th, 2010, 10:14 PM

I had a scan with my son at 36w 4days and he was approx 3.6kg. We had him by c-section (planned) at 38w 4d because every time my Ob scanned me she could tell he was growing VERY fast, plus my BP was up. He came out 4.154kg andI was told there was no way I could of had him naturally as his head was already stuck in my pelvis.
Good luck!! Big babies are great!! He was in 000 by the time he was 3 weeks old...hehe...fatty bumba!

**appletree** · July 9th, 2010, 10:31 PM

I had a growth scan at 36 weeks for DS where they said he was already 4kgs, he was born 4 weeks later at 4.62kgs, so i am guessing it was fairly accurate.

At the time i chose to believe it was inaccurate + or - 10%, and tried to convince myself that he was no more than 3.6kgs. The hospital still managed to unnecessarily try to scare the cr@p out of me with this info and then to try to talk me out of a VBAC.

**Alan** · July 9th, 2010, 10:49 PM

This is an extract from their own policy yet they still try to give a birth weight

Australasian Society for Ultrasound in Medicine
Policies and Statements
D7

Statement On Normal Ultrasonic Fetal Measurements

June 1991, Reaffirmed May 1996, Revised May 2001

FETAL WEIGHT
No formula for estimating fetal weight has achieved an accuracy which enables us to recommend its
use.

**~Kaz~** · July 9th, 2010, 11:15 PM

Why am I not surprised Alan??

Y'know, I didn't have a dating scan beyond 18-20 weeks and my doc didn't try to estimate DS's size. I was grateful cause I didn't really need the stress of having a number and having no idea how accurate it was. They should all stop doing this (throwing numbers around willy nilly) imho.